Which of the following is the main function of the skin?

Correct Answer: A

Rationale: Rationale: A) To protect the body from harm: The skin acts as a physical barrier that protects the body from external threats such as pathogens, UV radiation, and physical injuries. It helps prevent infections and dehydration, making it a crucial function of the skin. B) To regulate body temperature: While the skin does play a role in regulating body temperature through processes like sweating and vasodilation/vasoconstriction, its primary function is protection. C) To produce hormones: Hormone production is primarily carried out by endocrine glands such as the pituitary gland, thyroid gland, and adrenal glands, not the skin. D) To sense touch, temperature, and pain: The skin contains sensory receptors that allow us to perceive touch, temperature, and pain, but this function is secondary to its main role of protecting the body from harm.

Correct Answer: A

Rationale: Transverse waves are characterized by particles moving perpendicular to the direction of wave propagation. In transverse waves, the oscillations of particles are perpendicular to the direction of energy transfer. Longitudinal waves have particles that move parallel to the direction of wave propagation. Electromagnetic waves are a type of transverse wave that do not require a medium for propagation. Surface waves combine both longitudinal and transverse motions and occur at the interface between two different mediums.

Correct Answer: D

Rationale: The brain is a vital organ that requires robust protection, which is provided by a combination of structures. The skull acts as a hard, protective covering for the brain, shielding it from external trauma and injury. The meninges encompass three layers of membranes (dura mater, arachnoid mater, and pia mater) that envelop the brain and spinal cord, offering additional protection and cushioning. Cerebrospinal fluid, a clear, colorless fluid surrounding the brain and spinal cord, acts as a shock absorber and provides nutrients to the central nervous system. The combined function of the skull, meninges, and cerebrospinal fluid ensures comprehensive protection for the brain, making option D, 'All of the above,' the correct answer. Choices A, B, and C are not individually sufficient to provide comprehensive protection, but together, they form a multi-layered defense system for the brain.

Correct Answer: B

Rationale: Mechanical waves, unlike electromagnetic waves, require a medium (such as air, water, or solids) to propagate. Sound waves are a specific type of mechanical wave that necessitates a medium, like air or water, for transmission. Electromagnetic waves, on the other hand, can travel through a vacuum as they do not rely on a medium for propagation. Choice A (Electromagnetic waves) is incorrect since they do not require a medium to travel. Choice C (Sound waves) is partially correct in that it is a type of mechanical wave that needs a medium but is not the only type. Choice D (Both A and C) is incorrect because electromagnetic waves do not require a medium, only mechanical waves like sound waves do.

Correct Answer: B

Rationale: When the speed of a wave is constant and the frequency increases, the wavelength must decrease to keep the speed constant. The speed of a wave is determined by the product of frequency and wavelength (speed = frequency x wavelength). If the frequency increases while the speed remains constant, the wavelength has to decrease proportionally to maintain the speed unchanged. Therefore, as the frequency increases, the wavelength decreases to ensure that the speed of the wave remains constant. Choice A is incorrect because as frequency increases, wavelength decreases. Choice C is incorrect as the wavelength cannot remain the same when frequency increases while speed is constant. Choice D is incorrect as the wavelength cannot become zero under these conditions.